Mysterious 3 Ways Switches

malibujason79November 20, 2010

Hello everyone and thanks for taking the time to read my post. Bought a house a few months ago that is 7 years old. In the main living area I have two 3-way switches that I have no idea as to where they go or what they control. If I take my fluke voltage alert tester "lights up red when voltage in present" remove the switch covers and operate the switches, I can get it to light on and off when I toggle the other switch. So I know these are tied together. How can I go about finding what these switches control? The wiring is going through the walls not the attic or basement, so I can't physically trace them that way. Any input would be great.

Sorry I should of mentioned in my first post, that was the first thing I did. I also went around with one of those little 3 light wiring testers to make sure all the outlets are wired corectly. I'm wondering if there should be another 3-way switch some where in the circuit that was replaced with a single switch. Or maybe an outlet was replaced some where and they didn't break the little clip on the side of the outlet.

The most likely explanations have already been offered. It could be that the original wiring has been altered since installation. Seemingly mysterious switches are often installed for good reasons. I did one house where the owner wanted a 3-way switch for the front porch light with one switch in the rear hallway of the house so that the light could be operated with no one anywhere near the front door.

To add further on the possibility of it being for half of a duplex receptacle, if the receptacle was previously replaced and the 'common hot' tab not removed, it would negate the function of the switches and the receptacle would remain hot.

The first 3-way switch will have one hot lead coming in and one hot lead going out. The other outgoing lead would be hot, instead, if the switch were in the other position. The second switch will have two attached wires coming from the first switch, one of wich will be hot one hot, and depending on the switch position, one or no hot leads going out. To better visualize and understand how this works, I recommend getting an illustrated book on basic wiring. (Sorry, I'm not up on how to post graphics here.)

Switch one looks to be wired and working correctly. Switch two also looks to be wired correctly however the commom terminal which should be my output to what i'm controling is hot all the time. So I removed the common wire from switch two and connected a test light. Both switches work the test light as they should. So now I need to figure out what these switches control to see why I have an extra hot back feeding to my switch. I'm still think its a receptacle somewhere. FYI, I used this wiring diagram to help me trouble shoot this problem. http://www.electrical-online.com/extra-graphics/3wayswitch.htm